1. Field of the Invention
The present invention relates generally to hole saws and more specifically to a hole saw having efficient slug removal, which allows a slug to be removed from the hole saw without the use of additional tools.
2. Discussion of the Prior Art
The most common type of hole saw is a cup with teeth formed on the open end, a shank attached to the other end of the cup, and a drill retained in the shank. The drill starts the hole cutting process by providing a pivotal anchor for cutting the hole with the cup. However, an aggravating problem encountered with hole saws is the removal of a hole slug from the cup. Depending upon the material of the hole slug, removal of the slug can be a major challenge. If the material is plastic, the plastic hole slug will heat bond to the inside surface of the cup. There are numerous solutions proposed for removal of the hole slug. The simplest method of slug removal is to form openings in the top and/or side of the hole saw to allow the slug to be pushed or pried out with a tool.
U.S. Pat. No. 3,265,104 to Gallo, Sr. discloses a tubular saw cutter with chip removal means. A third embodiment of the Gallo, Sr. patent includes a rotary saw holder in which the center guiding means is a wood drill bit or the like surrounded by a spring and in communication with a double disc. The spring and the double disc act to dislodge a hole slug from inside the rotary saw holder. U.S. Pat. No. 5,934,845 to Frey discloses a hole saw with modified pilot and plug biasing. The Frey patent includes a mandrel having a central pilot drill bit having a tapered shank to facilitate removal of the plug from an annular cutting saw blade. A helical spring is preferred coaxially mounted between the saw blade and the pilot. The spring biases the plug as the hole is being cut and automatically ejects the plug from the saw.
Accordingly, there is a clearly felt need in the art for a hole saw having efficient slug removal, which utilizes a spade bit instead of a location drill and allows a hole slug to be removed from the hole saw without the use of tools.